Control valve for air brakes



July 17, 1923. 1,461,845

W. HILDEBRAND CONTROL VALVE FOR AIR BRAKES Filed Jul-y 21 1920 lllllllhl/l/ Patented duly l?, 1923..

untreu stares earner wiLHELi/r iariiinnnnaivn, or Lrcnrniiisiiiie, tenermi, anni/rant?, fissienon 'ro irnonnianiaivisn eirrrnncnsniirseirarr, or iiiciirniiisniae, anemia, GERMANY.

CONTROL VALVE AR To all whom t may concem Be it knownthat l, llViLrIiiLM` HILDEBRAND, a citizen oli' the German Republic, residing at Neue Bahnhofstrasse 9`17Lichte1iberg, Berlin, Germany, have invented certain new and useful lmprovements'in or Relating to Control Valves for Air Brakes ('l'or which l have received patents as follows: Germany,

No. 296,810, dated 19th May, 1916; Austria, .No 76,620, dated 23rd November, 1916; Huny gary, No. 7 3,927, dated 24th November, 1916 IGrreat Britain, No. 106,464,dated 13th December, 1916; Sweden, No; 44,869, dated 6th December, 1916; and Finland, No. 7,802, datedJune 21st, 1919), of which the following is a specilication. y

In the so-called brake-accelerators, in which the main brake-pipe is exhausted intoa chamber, this chamber` is constructed of such a size that when moving the controlling piston in the braking position ay also a corresponding decrease ot' ypressure iny 'the pipe, if bralrepipe vehicles are included in the train in question, these are also `pro vided with brake-accelerators.

In consequence of this large removal ct brake-pipe air the pressure in the pipe is reduced by at least halt an atmosphere on the slightest application of the brake, so that the smallest degree of braking causes a disproportionate effect. This is a great disadvantage, especially when travelling on rather slight down grades, as on these the train, by the action of even the smallest braking elfect, may be brought to a standstill. y

ln the arrangement of bralraaccelerators Jfor service brake applications it has been considered necessary to draw oil for each vehicle a certain large quantity of air from the pipe, in order to augment and accelerate thereby the wave of air produced from the itootplate outwards in the pipe. l'lowever experiments have proved that apart from Application filed July 21,

1920. Serial No. 398,037.

f the large removal ot bralre-pipe-air employed-in quick-actionbralrings but generally inadmissible inservice brakings, no accelerationo-f `the air wave is produced by the` cniployinelntoi chambers into"which the main-brake pipe is exhausted, so thatv for' instance the lair-wave in atrain equipped with brake accelerators of this ,kind does not reach the end oit the train any more quickly than if all the control valves andbralreaccelerators were switched oil' from the `binaire-pipey in question.

According to the present invention eX- pansion chambers are not employed to eXT haust the laialrei aipe,biit only to remove the disturbing intluence which the volume oft air expelled by the controlling pistonioi' the control valve in braking would exert on the `wave, of air passingl rapidly through the` pipe.` The chamber is accordingly only madeol: such a size that `it can take in the controlfpiston 'displacement volume or alit-v 'tle more` lt when effecting a bral e-application the Controlling piston of the first. `braked vehicle is `rfwersedinto the braking y position. and consequently the piston chamber is connected with the expansion' chainber, the piston-displacement-volume ofthe vformer is taken in by the latter, and is'not,

`as with ordinary control valves,compressed into the bralrapipe, so that the wave ot air moving along the train pipe can pass without hindrance right to the end ,ofthe train. A great advantage is thereby attained `in `that the lowest degree of ,braking isnot et- `tected by the expansion chamber, but is only dependent on the volume ol` airallowed to escape trom the brake pipe througli'the drivers brake valve. llt is then a matter of indifference whether the expansion chamber is exhausted in intermediate positions or in the release position ot the control piston, as the control pi ston-displacement-volume taken up by the expansion chamber can have little or no influence on the magnitude of the degree of" bralringl.

l will describe with reference to the accompanying drawing a construction in accordance with this invention but l do not limit myself to the precise construction` valve part of the control valve in the bralrlll) Yas

ing position in two differentk parallel sectional planes. i 'y Referring to `the drawing the 'control valve consists as heretofore of a casing a, a cover Z), a control piston c, a slide valve Z and a graduating valve e. At L is attached the brake pipe, which through a passage Z, Z communicates with the chamber I to the left of the piston. The chamber II to the right of thepiston is connected with they auxiliary airreservoir. At B, (Figure 3), the brake-cylinder is attached. yThe openvingA leads to the open air. The casing a contains the vexpansion chamber 2.' This communicates, as will be seen 1n Figure l,

in ythe release position, through the passage 3 ofthe slide valve andthe passage 4, with the open air.V If air, for the purpose of applying the brake, is let out of the pipe, the control piston goes to the left-hand end position and displaces the slide valve CZ with the graduating valve e into theJ position shown in Figures 2 and 3. The expansion chamber 2 is connected through Ithe passage 3 of the D slide valve with the passage 5 leading'to theipiston chamber I'. Conse- ,the auxiliary air reservoir communicates in quently the air driven out of the chamber I` bythe piston c entersthe expansion chamer 2, so that it is'not forced through the ,passage Zinto the brake-pipe. In this po` sition of the brake, as is shown in Figure 3,

the usualmanner through the` graduating valveie,.,slidevalve passage 6 and passage 7, withthebrake cylinder.

, The constructional example ,shows` a con trol valve with onlyonebraking position, in A whiclfi the expansion chamber '2 can of course` only communicate with the atmos-1 phere in the release position, since no other position is provided for the purpose. The

method of operating they valve is of course not of Yany consequence, as the` capacity Vof the chamber 2 onlyk corresponds to the volume of the chamber I and on vthis account cannot exert any Vinfiuence on the fallof pressure in the pipe and therefore' on the `degree of,v braking.v

inlet'located permanently in front of said v piston and an outlet controlled by said slide valve and adapted to place said expansion chamber in direct communication through said slide valve with said piston chamber.

2. In a control valve for air brakes, a casing containing a piston chamber, a piston movable therein, and a slide valve'adapb ed to be actuated by said piston, in combi- `nation with an expansion chamber normally open to the atmosphere, saidl casing ybeing provided'with a passage forming an open communication between said piston chamber and the mainbrake pipe, and also with a separate passage leading from the front to the back of the piston, said last" named passage being controlled by said slide valve and adapted to place said expansion chamber in direct communication with said Ypistonchamber, said slide valve being also adapted to close the atmospheric connection of said expansion chamber when opening said passage between said expansion cham-` ber. and piston chamber.

3. A control valve for air brakes having in conbination with a casing a piston cham* ber, a piston movable therein, a slide valve actuated by said piston, an expansion chamber and a passage to atmosphere, and means in said chamber and slide valve for forming communication of the expansion chamber with the piston chamber at one position of the said slide valve and the said passage at another position of the said slide valve.

WILHELMHILDEBRAND. 

